Aircraft propulsion systems may include gas turbine engines that are used to power the aircraft. Gas turbine engines typically include a compressor, a combustor, and a turbine. The compressor compresses air drawn into the engine and delivers high pressure air to the combustor. In the combustor, fuel is mixed with the high pressure air and the mixture is ignited. Products of the combustion reaction in the combustor are directed into the turbine where work is extracted to drive the compressor and, sometimes, a fan module coupled to the turbine by an output shaft. Left-over products of the combustion reaction are exhausted out of the turbine and may provide thrust in some applications.
Gas turbine engines may be used to power engine accessories and/or aircraft accessories. Depending on flight conditions, gas turbine engines may be required to provide thrust for the aircraft and/or power the accessories. Designing aircraft propulsion systems to satisfy aircraft thrust requirements while providing adequate power for accessories during various flight conditions remains an area of interest.